At the start of the game ask very nicely if a few people would come with you to IB tower to mess with allies, no not mention defence or honor famers will start the flame as they don't want to play like real men.
Ask for like 3-4, you will go there and a few more will follow. When people die they will join you and can quickly work up a good defence. Remember the best way to play the horde is to avoid going past icewing bunker like the plauge. After that bunker all the alliances outright rediculos advantages start, use scorched earth like a real man.
Remember don't come on like this is defence or you want a solid or large number. Don't demand this either.